Golfers have long known that the location of ball-club impact on the face of a golf club materially affects the direction of travel and initial velocity of the golf ball after impact. Initial velocity, in turn, affects the distance the ball will travel. The optimum location for ball-club impact is generally centrally of the club face and has come to be known as the "sweet spot." The further the point of actual impact between the club head and the golf ball from the sweet spot, the greater the degradation in initial velocity, as well as the greater the likelihood of a misdirected ball.
In recent years, manufacturers of golf equipment have designed clubs as as to increase the size of the sweet spot, or otherwise minimize the degradation on trajectory as the point of impact moves away from the sweet spot. While this effort has unquestionably been successful, it nonetheless remains an object to make contact with the ball at the sweet spot; and failure to do so will result in a poorly directed shot and/or one with reduced distance.
By way of example, for a right-handed golfer, a ball hit off the toe of the club will frequently travel in a line to the right of the intended path of travel for a reduced distance, the degree of which is determined by the club being used, the strength of the golfer, etc. Similarly, for a right-handed golfer, a ball hit off the heel of the club frequently will be "pulled" to the left of the intended line of flight and even when that does not occur, the ball will frequently take an unusually low trajectory of shorter distance than had the ball then impacted at the sweet spot.
Balls that are hit "thin," that is, below the sweet spot, tend to take undesirably low trajectories for the club being used. Depending upon the club being used, the ball may travel a greater or lesser distance than desired in such a case. Similarly, where the ball is impacted above the sweet spot, the result is frequently a ball hit highly in the air and which will travel a far lesser distance than intended.
Because of the unquestionable connection between ball trajectory and point of impact on the club face, many efforts have been made in the past to provide a means whereby a golfer can obtain an indication of the point of contact of a club head with a ball. Upon observing the point of contact, the golfer is then supposed to make whatever adjustment might be indicated by the deviation of the point of impact from the sweet spot, and thereby correct his swing. One approach is illustrated in U.S. Pat. No. 3,081,091 issued Mar. 12, 1963 to Grow. Grow provides a ball that is filled with a finely divided pigmented material, and which includes a maze of apertures. The ball is placed so that the apertures face the club head. When the ball is impacted by the club head, a small amount of the finely divided material within the ball is forced out of the apertures as the ball is compressed by the impact, and coats the point of contact on the club head. This coating is then observed by the golfer and an appropriate correction made, if necessary.
The Grow approach has a major disadvantage in that it requires the use of a ball that is not a conventional golf ball. By the very nature of its construction, the Grow ball will not follow a trajectory like a conventional golf ball and, as a consequence, the golfer may be unable to correlate the trajectory of the ball with the point of impact on the club face. Thus, lacking the ability to make a positive correlation, the Grow system is ineffective.
Another approach is suggested by Brandell in U.S. Pat. No. 3,806,132 issued Apr. 23, 1974. Brandell provides stickers having adhesives on both sides. One of the adhesives has a light tackiness, while the other has a medium tackiness. The light tackiness side of the sticker is adhered to a golf ball at the location where a club will impact upon it. Upon being impacted by a club head, the medium tackiness adhesive overpowers the light tackiness adhesive with the result that the sticker transfers from the ball to the club face at the point of contact. This system allows the use of a conventional golf ball enabling the golfer to correlate the point of impact with trajectory, but manipulation of the sticker is inconvenient and makes the system generally undesirable.
Still another approach is suggested by Dilny in U.S. Pat. No. 4,676,508 issued Jun. 30, 1987. Dilny provides a golf ball having a permanent outer coating of polyurethane resin that includes aluminosilicate and titanium dioxide. When impacted by a club head that evidently must be formed of glass fibers or carbon fiber and a suitable binder, the ball will leave a removable deposit of its coating on the club face to provide an indication of the point of contact. While Dilny represents considerable improvement over other prior art devices, it still has a number of drawbacks. For one, it is not useable with conventional golf balls in the sense that the golf ball itself must be provided with the requisite coating, apparently during the manufacturing process, because it is permanent.
Secondly, it appears that Dilny requires the use of golf clubs that are made-up of fibrous composite material and thus would not be effective with many conventional materials utilized in the manufacture of golf club heads, such as persimmon and various metals.
The present invention is directed to overcoming the above problems.